Device for mass and heat transfer

ABSTRACT

Apparatus for transferring heat and/or mass in fluid to fluid contact apparatus wherein at least one fluid is liquid, comprising a housing in which a plurality of transfer sections are tandemly arranged. Each transfer section comprising a plurality of vertically disposed planar structures spaced from each other by spacers having projections forming gaps for flow of one fluid. The housing being spaced to provide for movement of the other fluid from between the planar structure of one to those of another.

Jan. 1, 1974 United States Patent 1191 Kolar [54] DEVICE FOR MASS ANDHEAT TRANSFER 3,316,064 4/1967 Kuzuoka 6t 261/112 2 l. l l 6 2 Loetel etal........

lnventor: Vaclav Kolar, Prague,

Czechoslovakia 2 1970 Osdor..........................:::....261/112FOREIGN PATENTS OR'APPLICATIONS Assignee: Ceskoslovenska Akademie ved,

Prague, Czechoslovakia Nov. 23, 1971 Appl. No.: 201,307

Filed:

Related U.S. Application Data Primary Examiner-Tim R. Miles [63]Continuation-impart of Ser. No. 149,244, June 2,

1971, abandoned.

Attorney-Richard Low and Murray Schaffer [57] ABSTRACT Apparatus fortransferring heat and/or mass in fluid to [30] Foreign ApplicationPriority Data J 8, 1970 C h l vak" 4006 70 une Zec 050 m I fluid contactapparatus wherein at least one fluid 1s 52 us. 261/112 "quid, Comprisinga housing in which a plurality of 511 1111.130113/04 swims are tandemlyarranged Each transfer 5 Field f searchmu 261M 12 section comprising aplurality of vertically disposed planar structures spaced from eachother by spacers [56] References Cited having projections forming gapsfor flow of one fluid.

UNITED STATES PATENTS The housing being spaced to provide for movementof the other fluid from between the planar structure of one to those ofanother.

261/94 9 Claims, 6 Drawing Figures Thomas Hamon Eckert 4005 456 999 HHH552 750 504 7614 42.7- 2. 223

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saw u or 4 mm mm INVENTOR ORN Y DEVICE FOR MASS AND HEAT TRANSFER Thisis a continuation in part of US. application Ser. No. 149,244 filed June1, 1971 now abandoned for which all legal and equitable rights andprivileges are claimed.

BACKGROUND OF THE INVENTION The present invention relates to a devicefor mass and heat transfer between two immiscible fluid phases of whichat least one is a liquid.

Columns which contain a packing material represent one of the mostwidely used types of devices for mass and heat transfer between liquidand gaseous phases, such as for example, in rectification and absorptionor between two immiscible liquid phases, such as for exampleliquid-liquid extraction. In devices of this type, intensive contact ofthe respective phases is accomplished by the fact that the liquid flowsover the surface of the packing material which is of a suitable shape inorder to produce the largest possible interphase surface. The mostcommon type of packing material is a layer of a lumpy material whichcontains discrete particles of different sizes and shapes to form asphere, a Raschig ring or a Berl saddle and the like. A disadvantage ofthis type of packing resides in the fact that it presents a considerablyhigh resistance to the passage of phases and only a relatively smallpart of the entire surface of the packing is effective.

The first of the above mentioned drawbacks is eliminated in accordancewith some device by a packing consisting of blocks of vertical platesdisposed in parallel relationship and filling the entire device. Thesecond of the above mentioned drawbacks cannot be removed at all, or atbest only partly with hitherto used wetting methods. The liquid beingprocessed which has to produce a continuous film on the verticalsurfaces is supplied in the form of a spray on the upper edge of thepacking so that individual drops or small liquid sources are createdwhich do not form a continuous film on the vertical surfaces but usuallya number of small streams which unite only accidentally into acontinuous film. Moreover, conditions are such that they do not ensure,after a suitable time, homogenization of the liquid. Thus reduction ofthe concentration or temperature gradient and creation of a newinterphase surface results. I

It is a general object of the invention to eliminate the above mentioneddrawbacks of known types of mass and heat transfer devices.

Another object of the invention is to provide a novel and improveddevice for mass and heat transfer between two immiscible fluid phases atleast one of which is liquid by providing a contact column comprisingsections of vertical or substantially vertical plates in combinationwith a liquid distributor.

Yet another specific object of the invention is to provide a device formass and heat transfer of the above mentioned type wherein the bottom ofthe liquid distributor is formed by the upper edges of the plates andflat spacer strips, the latter being provided on both sides withprojections which form slots or gaps for the passage of liquid.

Still another object of the invention is to provide a device of theabove mentioned type in which the plates are made from expanded metaland in which substantially deflected ribs replace the projections of thespacing strips.

These objects together with numerous advantages will be apparent fromthe foregoing disclosure of the present invention.

SUMMARY OF THE INVENTION According to the present invention mass and/orheat transfer apparatus is provided comprising a housing adapted toreceive a primary fluid at one end and a counter flowing fluid at theother end. Stacked in a column within the housing are a plurality ofheat or mass transfer sections each comprising a plurality of planarstructures disposed vertically with respect to each other and havingmeans for spacing them apart and for providing distributing passages forthe primary fluid. The housing has an enlarged portion surrounding thejuncture of adjacent transfer sections to form a partial chamber formovement of the counter flowing fluid from one section to another.

At least one of the fluids must be liquid, preferably this is theprimary fluid, while the counter flow fluid may be vapor, gas, orliquid. The planar structures may be sheets or plate like members or mayeven be expanded metal sheets. The structures are provided with spacershaving projections forming the passages between them.

Full details of the present invention follow in which reference is madeto the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 represents an isometric view partially in section of one transfersection including planar structure and distributor of liquid;

FIG. 2 is a schematic illustration of the flow of gas through a deviceemploying the transfer sections according to FIG. I;

FIG. 3 shows one embodiment of spacing strips;

FIG. 4 shows another embodiment of spacing strips;

FIG. 5 is a schematic illustration of expanded metal employed in thepractice of the invention; and

FIG. 6 illustrates another embodiment of spacing strips.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now more particularly toFIG. 1 there will be seen a subassembly comprising a plurality ofvertically disposed planar structures 1 forming the individual transfersections of a fluid contact apparatus. The planar structures areseparated at their upper ends by spacing strips 2 each of which isprovided with laterally extending projections 3 forming fluiddistributing openings 0 along the sides of the plates 1. The upper edgesof the planar structures 1 and the spacing strips 2 are horizontallycoplanar and form the bottom of a distributor section enclosed by atrough or vessel 4 formed by peripheral sides 9. Opposed sides of thetrough 4 are provided with runners or slats 5 for supporting andsuspending the underside of the sub-assembly of planar structures 1 andspacing strips 2 in vertical spaced arrangement.

The trough or vessel and the supporting slats 5 are arranged so as tobind the assembly of planar structures and spacers, tightly an unitarilytogether, so that the assembly is rigid and permits flow of fluid onlythrough the gaps 0 formed by the projections 3.

As seen schematically in FIG. 2 a plurality of the subassemblies arevertically arranged in tandem or stacked relationship in a housing 6,itself formed of a number of vertical sections having enlarged portions7 at each end. The enlarged or widened portions 7 abut against eachother, and are sealed by extended flanges so as to form a pass chamber10 partially surrounding the junction of the distributor sections and onthe one hand the upper edges of the plate structures 1 and on the otherhand the bottommost edges of the plate structures of each adjacentsub-assembly. The sections of the housing 6 are joined together at theirflanged ends by conventional means. Means for providing a primary fluid,for example at the upper end and a counter flowing gas or fluid at thelower end are also provided in conventional manner, although not shown.

FIGS. 3 and 4 show spacing strips 2 provided with various projections'3. The projections seen in FIG. 3 are those shown in FIG. 1 andcomprise a plurality of parallel vertical ribs integrally formed inuniform spaced relationship on both sides of the spacers. Thus a singlespacer can provide distributing openings or gaps on either side betweenadjacent projections. In FIG. 4, the projections comprise wire likemembers 3 wound through an elongated rectangular spacer member 2 andknotted or twisted into place in uniform spaced relationship. This alsoprovides the necessary projection to provide distributing openings 0.

In FIG. 5 an alternate form of plate structure is shown which comprisesa structure formed of expanded metal having a lattice work ribconfiguration. The exact lattice configuration is not critical and whilethe diamond shape is shown, others may be used. At least some of thelattice ribs are deflected spatially out of the plane of the expandedmetal, as seen in the twist of portions 11 so that even though the upperedges of the structure 1 may be squeezed between the spacers 2 the fluidmay be caused to run in twisted contortions down the lattice work. Inthe use of a lattice plate structure the projections 3 may be reduced insize or eliminated, since the open lattice will provide sufficient gapspace.

FIG. 6 shows another alternative construction for spacing strips 2" inwhich openings 8 are provided. The openings serve as passages bringingone of the two phases above the level of liquid in the distributor. Ifthis construction is used then the widened part 7 of the container 6 mayno longer be necessary.

In operation a primary liquid is delivered into the trough or vessel 4of the uppermost sub-assembly of the assembled contact apparatus seen inFIG. 2. The liquid is passedthrough the gaps 0 formed between the plates1 and spacers 2 and descends in a uniform distribution onto theplates 1. The arrangement of the plate and spacers creates an effectivedistribution of the liquid, forming a thin cohesive film on the surfacesof the plate structure 1. Meanwhile a counter-flow of fluid, such asgas, vapor, or liquid itself which is immiscible with the primary liquidis delivered and caused to ascend upwardly in contact with the primaryliquid. The counterflow liquid by passes the distributor section bytaking the path shown by the arrows through the widened or enlargedsection 7. During passage of the primary fluid through the housing, incontact with the counter-flow fluid, the required and desired transferof heat and/or mass occurs.

The arrangements described permit building in of a considerableinterphase surface which readily lends itself to substantially perfectuse for mass or heat transfer as described earlier. If expanded metal isused as the plate, there occurs interrupted mixing of the liquid in thefilm as it descends and thus renovation of the interphase surface andincrease of the driving force for mass or heat transfer occurs.

The arrangement of the inserted structure in a column of circular crosssection is analogous and obvious in view of the above disclosure.

It will be seen that the present device provides a liquid distributorarranged above each section of the transfer structures. This serves tosubject the descending fluid to repeated homogenization and mixing. Italso serves to balance concentration and temperature gradients. I

The provision of projections on the alternating spacer strips in theform of ribs or wires arranged in the direction of flow of the liquidenhance fluid flow. They also provide means for clamping thesub-assembly together in a tight unit with the fluid passagesselectively dimensioned to obtain a desired or predetermined flow rate.

Another feature of the invention lies in the fact that the distributorof the device is a vessel, the bottom of which is formed by the upperedges of the plates and by flat spacer strips, so that the fluiddescending from one section to another collects in the vessel and isredistributed more uniformly.

An important advantage of the invention resides in the fact that thereis created on the sheet like plates a continuous film of the liquid oron the expanded structure a number of small sources or streams whichnecessarily unite into a continuous film after passing through theoutlets or gaps in the distributors at the upper end of each transfersection.

When the liquid film flows down over a path formed by the length of theplates it either flows away from the device, or into another distributordisposed in a lower position. In each distributor, homogenization of theliquid and balancing of concentration and temperature gradients occursand a new interphase surface is produced at the outlet of the passages.At lower wetting densities of fluid it is at first desirable to increasethe wetting density whereby perfect wetting of the surface is achieved,and this interphase state is maintained even if the wetting density isreduced.

Experiments have shown that even a thin layer of the liquid leads to asubstantial increase in the coefficient of mass or heat transfer, if bysuitable arrangement of the surface of the transfer plate structures(roughness, perforation, and the like) or mechanical stirring goodmixing of the liquid in the layer is achieved as it flows over theinserted structure, and thus a reduction in the concentration ortemperature on the interphase surface results. This increases theconcentration or temperature gradient, and therefore also the drivingforce of the process.

Experiments have also shown that expanded metal is an eminently suitablematerial for achieving the above mentioned turbulence of the liquidlayer.

Table 1 shows values of the coefficient of mass transfer in m/s (per 1 mof inserted structure) measured on a device with different types ofpacking in a water carbon dioxide system. The plates were mm wide and750 mm long and they were wetted on both sides.

TABLE 1 Type of packing Rate of flow of water 1 l/min Time 0.l 0.5 1.05.0 Smooth plate 6.4Xl" 9.0 l0* l.5 l0 Perforated metal l.7 l0 3.0Xl0"8.0Xl0 sheet dia. 8mm Perforated metal sheet dia. 4X4 mm 4.0)(10' 2.0 l02.9Xl0" 5.3 l0

Perforated metal sheet dia. 6.75X6.75 mm it is obvious from the abovementioned table that the coefficient of mass transfer is, underotherwise similar conditions up to eight times larger for expanded metalthan with a smooth plate, and, on an average, about 30 percent largerthan with perforated surfaces having circular holes which appear to bethe most effective among perforated metal sheets.

Moreover, in addition to an increased efficiency the use of expandedmetal as a packing has another advantage in comparison with perforatedmetal sheets. This advantage arises from the fact that no material wasteoccurs in production. On the contrary, an areal unit of the metal sheetyields a multiple of the area of expanded metal. In view of the factthat in production spatial deflection of the ribs occurs thinner metalsheets may be chosen for production without endangering the stability ofthe packing. Spatial deflection of the ribs makes possible a moreperfext mixing of the liquid film than plane bridges in perforated sheetmetals. Best results were obtained with an arrangement where the liquidflowed in the direction of cut of the sheet.

It will thus be observed that various modifications and changes arepermissible without departure from the scope of the present invention.Accordingly the present disclosure is to be taken as illustrative onlyand not limiting of the invention.

What is claimed is:

1. Apparatus for the mass or heat transfer between fluid phasescomprising a. a vertical housing adapted to receive a primary fluid atits upper end for downward flow and a secondary fluid at is lower endfor flow upwardly counter to said primary fluid,

b. a plurality of transfer sections arranged adjacent each other intandem within said housing, each of said transfer sections comprising 1.a plurality of vertically disposed substantially planar structures 2.spacer means located between said structures along one edge thereof forseparating said planar structures from each other providing distributingpassages for flow of primary fluid thereover,

c. said housing having an enlarged portion surrounding the juncture ofadjacent transfer sections with said spacer means and forming a chamberfor movement of said counter flow fluid about said spacer means from thestructures of one section to the structures of the adjacent section,said spacer means defining with said structures vertical openings alongthe faces of said structures.

2. Apparatus according to claim 1 wherein said spacing means comprise anelongated strip interposed between adjacent planar structures and havinglaterally extending projections forming fluid passages between saidstructures and said strips.

3. Apparatus according to claim 2 wherein said strips are arranged tohave their upper edges substantially horizontally planar therewith, andincluding peripheral primary fluid enclosing means whereby said fluidmay be distributed through said passages from the structures of onesection to the structures of another section.

4. The apparatus according to claim 2 wherein said projections comprisevertical ribs integrally formed on said spacer strips and uniformlydisposed along the length thereof.

5. The apparatus according to claim 4 wherein said projections comprisewire sections secured through said spacer strips and arranged uniformlyspaced in a vertical direction along the length of said strip.

6. The apparatus according to claim 1 wherein said spacing meanscomprises an elongated U shaped member having a plurality of holesformed along its length.

7. The apparatus according to claim 1 wherein said planar structurescomprise plate like sheets.

8. The apparatus according to claim 1 wherein said planar structurescomprise a sheet of expanded metal having a latice work of interconnected ribs.

9. The apparatus according to claim 8 wherein at least some of the ribsof said expanded metal sheet are deflected spacially out of the plane ofsaid sheet.

1. Apparatus for the mass or heat transfer between fluid phasescomprising a. a vertical housing adapted to receive a primary fluid atits upper end for downward flow and a secondary fluid at its lower endfor flow upwardly counter to said primary fluid, b. a plurality oftransfer sections arranged adjacent each other in tandem within saidhousing, each of said transfer sections comprising
 1. a plurality ofvertically disposed substantially planar structures
 2. spacer meanslocated between said structures along one edge thereof for separatingsaid planar structures from each other providing distributing passagesfor flow of primary fluid thereover, c. said housing having an enlargedportion surrounding the juncture of adjacent transfer sections with saidspacer means and forming a chamber for movement of said counter flowfluid about said spacer means from the structures of one section to thestructures of the adjacent section, said spacer means defining with saidstructures vertical openings along the faces of said structures. 2.Apparatus according to claim 1 wherein said spacing means comprise anelongated strip interposed between adjacent planar structures and havinglaterally extending projections forming fluid passages between saidstructures and said strips.
 2. spacer means located between saidstructures along one edge thereof for separating said planar structuresfrom each other providing distributing passages for flow of primaryfluid thereover, c. said housing having an enlarged portion surroundingthe juncture of adjacent transfer sections with said spacer means andforming a chamber for movement of said counter flow fluid about saidspacer means from the structures of one section to the structures of theadjacent section, said spacer means defining with said structuresvertical openings along the faces of said structures.
 3. Apparatusaccording to claim 2 wherein said strips are arranged to have theirupper edges substantially horizontally planar therewith, and includingperipheral primary fluid enclosing means whereby said fluid may bedistributed through said passages from the structures of one section tothe structures of another section.
 4. The apparatus according to claim 2wherein said projections comprise vertical ribs integrally formed onsaid spacer strips and uniformly disposed along the length thereof. 5.The apparatus according to claim 4 wherein said projections comprisewire sections secured through said spacer strips and arranged uniformlyspaced in a vertical direction along the length of said strip.
 6. Theapparatus according to claim 1 wherein said spacing means comprises anelongated U shaped member having a plurality of holes formed along itslength.
 7. The apparatus according to claim 1 wherein said planarstructures comprise plate like sheets.
 8. The apparatus according toclaim 1 wherein said planar structures comprise a sheet of expandedmetal having a latice work of inter connected ribs.
 9. The apparatusaccording to claim 8 wherein at least some of the ribs of said expandedmetal sheet are deflected spacially out of the plane of said sheet.